A common, safe and inexpensive drug for Type 2 diabetes, metformin, decreases the risk of heart attacks and strokes caused by air pollution and reducing inflammation in the lungs that triggers clotting, according to a U.S study.

In the study published in Cell Press, a paediatric formulation of metformin was given to mice in their drinking water for three days.

It was an equivalent concentration to the dose people take for diabetes and the mice were exposed to air pollution in a specially designed chamber that concentrates the particles.

When the mice were exposed to air pollution in the laboratory, their macrophages released an inflammatory molecule called IL-6, linked to heart attacks and strokes.

Metformin prevented the release of IL-6 and reduced the speed at which clots formed after an injury. The same findings were seen in lung macrophages from humans.

Three years ago, Northwestern University (NU) professor of Medicine and Cell Biology and his colleagues, Mr Chandel, found that metformin inhibits cancer progression.

They also discovered that metformin slows mitochondrial metabolism to prevent the growth of cancer.

To prove that targeting the mitochondria in macrophages could prevent inflammation in response to pollution, NU Professor of Airway Diseases, Scott Budinger and Chandel created mice where lung macrophages lacked key mitochondrial proteins.